U.S. Pat. No. 4,754,247 entitled "Molded Case Circuit Breaker Accessory Enclosure" describes a so-called "integrated" circuit breaker that provides both circuit interruption as well as accessory function. This Patent should be reviewed for its disclosure of an accessory cover mounted on the circuit breaker cover for providing access to field-installable accessory devices. The integrated circuit breaker includes an integrated circuit electronic trip unit which allows one circuit breaker design to be used over a wide range of ampere ratings in combination with a rating plug, also mounted in the circuit breaker cover. The electronic trip unit is described within U.S. Pat. No. 4,589,052 and the rating plug is described within U.S. Pat. No. 4,649,455.
The use of common circuit breaker components over a wide variety of ampere ratings could provide a strain on the circuit breaker case in the vicinity of the line and load terminal straps upon short circuit interruption when operated at high ampere loadings. The large electrodynamic forces exerted between adjacent line terminal straps and between adjacent load terminal straps exert corresponding large stress forces to the underlying case to which the line and load terminal straps are secured. U.S. Pat. No. 4,975,667 describes a glass-filled plastic inset that provides added strength to the line and load terminal straps to thereby allow common circuit breaker components to be used over a wider range of circuit breaker ampere ratings without adding to the circuit breaker cost.
The increase in the cost of the copper and silver materials used to fabricate the line strap components is reflected in the overall circuit breaker component costs. To reduce the number of components that must be inventoried, a large line strap that is designed for a 1600 ampere circuit breaker is also used within an 800 ampere circuit breaker. Since the remaining components are common within both circuit breaker designs, it would be cost beneficial to provide a line strap design that can be assembled from common lower current components and additively assemble the components to accommodate for the higher current rating.
Accordingly, one purpose of the invention is to provide a circuit breaker line strap modular assembly whereby the line strap components are additively combined for each circuit breaker ampere rating.